Field of the Invention
The present invention relates to a hybrid electric vehicle and a method of efficiently controlling transmission thereof, and more particularly, to a transmission control method that improves fuel economy when gear shift and engine clutch release are to be simultaneously performed and a hybrid electric vehicle capable of performing the same.
Discussion of the Related Art
In general, a hybrid electric vehicle is a vehicle that uses two types of power sources, which mainly include an engine and an electric motor. In recent years, research has been conducted into the hybrid electric vehicle, since the hybrid electric vehicle exhibits higher fuel economy, higher power performance, and lower discharge of exhaust gas than a vehicle having an internal combustion engine.
The hybrid electric vehicle may operate in two traveling modes based on the powertrain thereof. One of the traveling modes is an electric vehicle (EV) mode, in which the hybrid electric vehicle is driven using the electric motor, and another is a hybrid electric vehicle (HEV) mode, in which the hybrid electric vehicle is driven using both the electric motor and the engine. Based on traveling conditions, the hybrid electric vehicle performs switching between the modes. Particularly, in a hybrid electric vehicle using a parallel type or transmission mounted electric device (TMED) type hybrid system having an electric motor and an engine clutch (EC) mounted between an engine and a transmission, engine clutch release and gear shift may be performed frequently and simultaneously during switching from the HEV mode to the EV mode.
To improve ride comfort during gear shift, engine clutch release control is not performed when a shift event is generated, and engine clutch release control is performed after gear shift is completed. However, the engine remains unnecessarily connected to a driving shaft. In particular, fuel injection into the engine is continuously performed, thereby reducing fuel economy.